1. Field of the Invention
This invention relates to a recombinant electric storage battery which includes separators that retain a selected balanced quantity of electrolyte and has positive plates of high antimony content.
2. Description of the Prior Art
There has been considerable interest in developing recombinant electric storage batteries due to their maintenance-free capabilities, long life, and possible manufacturing economies. Recombinant batteries of the lead acid or nickel cadmium type which operate by recombining the gases generated during charging are known in the art.
Recombinant batteries usually operate on the oxygen cycle and are designed with an excess of negative material as compared with positive material. During charging the positive electrodes reach full charge and generate oxygen before the negative electrodes generate hydrogen. The batteries are designed for optimum oxygen movement to the negative electrodes for recombination with the negative material or with the generated hydrogen to form water. By recombining the oxygen the internal pressure in the battery is restrained, the cell can be sealed and the battery continuously charged.
Examples of prior art batteries are found in the following U.S. patents: Abramson No. 3,170,819; McClelland, et al. No. 3,704,173; McClelland, et al. No. 3,862,861; Peters, et al. No. 4,119,772; Habich, et al. No. 4,320,181; Peters, et al. No. 4,373,015; McClelland, et al. No. 4,383,011; and Pearson No. 4,525,438.
The use of antimony in the positive plates in a sealed lead acid battery is described in the Szymborski, et al. Patent No. 4,401,730 as an improvement where the antimony content of the positive plates is not more than 2 percent. The Szymborski patent also describes control cells which contain antimony of a 2.1 percent content, which cells are described as showing a marked decrease in capacity after 300 cycles, compared with the cells made by Szymborski, according to his invention, that contained 1.4 to 1.5 percent antimony.
It is known that adding antimony as a component of the positive plates of a lead acid battery improves performance, but it also increases the degree of gassing of the positive plates, and no satisfactory solution has been proposed in the prior art to accommodate the higher rate of gassing.
It has been found that lead acid batteries constructed with fibrous sheet plate separators, having first and second fibers of different absorbency relative to the electrolyte in order to control the recombination rate, can control the degree of gassing that occurs with antimony levels above 2 percent of total alloy weight.